Tyson Gay (L, orange shirt) besting Jamaica's Asafa Powell (red) in the 100 meters at the Diamond League meet July 4 in Lausanne, Switzerland. Both confirmed Sunday they have tested positive for banned substances.

Hey, pro cycling: move over on that trash heap, so there is some room for track and field.

Almost exactly a decade after the BALCO scandal all but destroyed track’s credibility, the sport is facing another legitimacy crisis.

Sunday, leading U.S. sprinter Tyson Gay and Jamaica's Asafa Powell, Olympic gold medalist and former world record-holder in the 100 meters, confirmed they have tested positive for banned substances. There were news reports saying Powell was among Olympic gold medalists from Jamaica who tested positive for stimulants at their national championships last month.

Add that to the doping mess in Turkish track and field, with doping charges brought against the 2012 women’s Olympic 1,500-meter champion and a two-time European hurdles champion, and the only thing worse for the sport would be if Usain Bolt tested positive.

Bolt’s agent, Ricky Simms, told the Tribune in an email that none of the athletes Simms represents had tested positive.

Gay's primary sponsor, Adidas, announced Monday it was suspending the contract.

It would be easy to say the Gay story was shocking, but it also might be disingenuous. The use of performance-enhancing drugs in the sport has been so widespread over the last 50 years that having another great champion test positive is about as shocking as the gambling in the movie, “Casablanca.”

All the facts of the Gay situation –including the confirming test of his “B” sample – are not in. But the reigning U.S. 100- and 200-meter champion will withdraw from next month’s World Championships, where his races against Bolt were expected to be among the highlights of the meet.

The surprising part of the Gay case is his willingness to take full responsibility for having the banned substance turn up in a May 16 out-of-competition drug test, even though he told reporters on a Sunday conference call there is an explanation that seemingly would suggest it was not his intention to dope.

The surprise there isn’t so great, either, since Gay always has been a stand-up guy

“I don’t have a sabotage story. I don’t have any lies,” Gay was quoted as saying.

“I don’t have any of those stories. I basically put my trust in someone, and I was let down.”

Gay, the 2007 world champion in the 100 and 200 and U.S. record-holder in the 100, would not identify the person in question. He indicated he would take any punishment “like a man.”

Defenders of track and field and cycling will be quick to say their sports catch people because their anti-doping efforts are serious, while pro sports like football, baseball, hockey and tennis have a wink, wink attitude toward use of PEDs.

No matter that such an argument is valid, it hardly absolves runners and cyclists of guilt for doping positives.

The anti-doping system has strict liability for anyone whose test comes back positive. Ignorance of what is in health supplements athletes use or what is in a substance recommended by a member of an athlete’s entourage is an explanation but not an exculpatory excuse.

The BALCO scandal – named for the California lab that helped design doping programs for athletes – began the undoing of several track athletes, including sprint superstar Marion Jones and another top U.S. sprinter, Kelli White, who had won the 100 and 200 at the 2003 world championships.

Three years later, U.S. sprinter Justin Gatlin tested positive for a steroid. Gatlin, then reigning Olympic 100 champion and reigning word 100 and 200 champion, vainly argued sabotage, served a four-year suspension and returned to win a bronze medal in the 100 at the 2012 Olympics.

Sunday, Powell's agent, Paul Doyle, confirmed in an email to the Tribune that Powell and Sherone Simpson had tested positive. The London Daily Telegraph identified Nesta Carter as another Jamaican positive. All had run on gold-medal Olympic relays. Monday, the Jamaica Gleaner reported two less distinguished athletes, discus throwers Allison Randall and Travis Smikle, were among the positives.

In a statement, Powell said he tested positive for methylsynephrine but had never "knowingly or willingly taken any supplements or substances that break any rules. I am not now - nor have I ever been - a cheat."

Last month, two-time Olympic 200-meter champion Veronica Campbell-Brown of Jamaica was suspended for a positive test that international track federation spokesman Nick Davies characterized as a “minor violation.”

At a certain point, minor and major just run together. The sport again is running off the rails, just as cycling did, with Lance Armstrong at the throttle of a train wreck.

Tyson Gay is no Machiavellian liar like Lance. Gay’s doping violation may have been as inadvertent as it seems.

Yet that does not change how suspicious Gay’s stunning comeback this season suddenly feels, no matter how likable a person he is.

In track and field as in cycling, it is sadly no longer possible to give the benefit of the doubt to anyone.

Only the doubt remains.

It will never go away.

For track and field, that can only hasten the death of a sport that already is on life support in the United States.